Britain's home secretary announced that she was cracking down on the "health tourists" who were using Britain's hospitals for free. The interviewer pressed her. How much money were these health tourists stealing from our pockets? May did not know. The Royal College of GPs, which ought to know, puts the cost at 0.01% of Britain's health budget – or next to nothing. When the European Commission asked Britain for proof that sly continentals were sneaking into our hospital beds, Whitehall replied that its demand for hard facts was an affront. "We consider that these questions place too much emphasis on quantitative evidence," it huffed.

Far from being embarrassed, Mrs May was triumphant. Feelings mattered more than facts. Her job as a senior politician with ill-disguised ambitions to become prime minister was to pander to popular prejudice rather than tell the public the truth.

People feel it is unfair that illegal immigrants can use services, she said. They "feel it's too easy to stay here illegally". They had the "feeling that people who are here illegally were accessing services", she continued, before degenerating into a babble of random noise, from which I just about made out that the "people" who had these "feelings" were, of course "hard working".

In For the Time Being, Auden has Herod explain why he must save the classical world by killing the infant Jesus. If religion triumphed, "Reason will be replaced by Revelation. Instead of Rational Law, objective truths perceptible to any who will undergo the necessary intellectual discipline, knowledge will degenerate into a riot of subjective visions... The Rough Diamond, the Consumptive Whore, the bandit who is good to his mother, the epileptic girl who has a way with animals will be the heroes and heroines of the New Age".

Mrs May can make you feel that way, as, indeed, can an hour spent watching prime-time television or reading the tabloid press. As Ukip threatens its core vote, the Conservatives will spend 18 months trying to flatter the deluded into voting Tory by telling them that they are right to put their "riot of subjective visions" before paltry facts.

In July, the opinion pollsters Mori innocently provided what now looks like a draft of the next Conservative manifesto when it published a list of popular misconceptions. Most people believed that crime was rising when it has been falling for years, it said. They overestimated the number of immigrants by threefold, the number of teenage pregnancies 25-fold and the amount of benefit fraud 34-fold.

If one wanted to fall into an Audenesque melancholy, one could note that the above is a mere taster of evidence-free beliefs. There is self-interested wrong-headedness. Ninety-seven per cent of climate scientists believe in global warming. But because combating climate change will be expensive and difficult, the American public prefers to think instead that scientists are split down the middle.

Public sector workers maintain that job losses will inevitably lead to poorer services. A BBC poll showed that a majority of the public had found that the overall quality of services had improved since the cuts began. Meanwhile, the British Bankers' Association and its backers in the Conservative party say that the only thing wrong with the public providing the City with subsidies on a Himalayan scale is that it encourages "destructive" outbreaks of "banker-bashing".

Religiously inspired wrong-headedness – the belief that a policy must be followed because a non-existent deity or manmade holy book mandates it – is becoming rarer in developed countries. But it can still motivate opposition to gay marriage in Europe and North America, while bringing terror and the denial of rights to hundreds of millions in much of the rest of the planet. Above them all stands the inability to think clearly about the despised minorities – foreigners, loose women, criminals and scroungers – that Mrs May was so anxious to endorse.

Everyone from money-grubbing TV executives to seedy politicians hit their critics with a dictionary of ready-made insults when you try to take these cognitive biases on. You are "an elitist" and a "snob" who lives in an "ivory tower". You "don't get it," and think you "know better" than the common people who make their choices in the ballot box or marketplace. Unless you are careful, the old reactionary argument that democracy is just mob rule can creep into your mind and you find yourself wishing for an enlightened dictatorship of experts and bureaucrats .

The road back to sanity begins by understanding that a free country is engaged in arguments that never end. We have been here before. In the 1990s, New Labour and the Conservatives dreamed up ever more ludicrous and ineffective anti-crime initiatives. Their arms race culminated on 6 December 2000 when Tony Blair asked the then Conservative leader William Hague why he had "made a policy-free speech apart from a load of nonsense from the shadow home secretary, most of which we are doing in any event".

That was a moment when the cynicism of the establishment was plain to see. Our leaders were treating the public as fools and offering policies they knew to be nonsense in the hope of conning them into the polling booths. Hearteningly, the public saw through the swindle. "Spin" became a dirty word. Populism became unpopular – turnout in elections collapsed – and self-defeating. Leaders who relied on fear were not believed when they said, truthfully, that crime had fallen. Worse than that, the politicians who wasted their days searching for "eye-catching initiatives", to use Blair's language, looked paltry and ridiculous figures even in the good times of the 1990s. How much worse will politicians such as May look when they play silly games in the middle of the worst economic crisis in a century?

Auden warned that when populist heroes are worshiped, "the general, the statesman and the philosopher become the butt of every farce and satire". If our statesmen (and women) choose to put feeling and prejudice before thought and evidence, however, a butt is what they deserve to be. Let us hope they become one. Let us hope that the mocking laughter becomes so loud it drives them out of public life.